Integrating multiple thin film resistors
Granted: February 15, 2005
Patent Number:
6855585
A method for forming multiple resistors on a substrate. The method initially includes providing a first resistor on the substrate. A first dielectric layer is deposited, patterned, and selectively etched over the first resistor. Second resistor material is provided over the first dielectric layer. Furthermore, landing pad material is provided over the second resistor material. The landing pad material and the second resistor material are then selectively etched. The selective etching…
Efficient minimum pulse spread spectrum modulation for filterless class D amplifiers
Granted: January 25, 2005
Patent Number:
6847257
Method and apparatus to enable the use of class D amplifiers without the need for an output filter, while maintaining both a high efficiency and a high audio fidelity. Using the classic differential Pulse Width Modulation scheme, the high frequency carrier is first suppressed to achieve a ternary modulation, and then re-introduced as a common mode pulse whose width is modulated to provide the necessary output voltage, but whose width never decreases below a well-defined threshold. The…
Microrelays and microrelay fabrication and operating methods
Granted: January 11, 2005
Patent Number:
6841839
Microrelays and microrelay fabrication and operating methods providing a microrelay actuator positively controllable between a switch closed position and a switch open position. The microrelays are a five terminal device, two terminals forming the switch contacts, one terminal controlling the actuating voltage on an actuator conductive area, one terminal controlling the actuating voltage on a first fixed conductive area, and one terminal controlling the actuating voltage on a second…
Low distortion current switches for high speed current steering digital-to-analog converters
Granted: December 21, 2004
Patent Number:
6833801
Low distortion current switches for high speed current steering digital-to-analog converters. The current switches use a compensation method for improving the spurious peformance of a CMOS current steering DAC for high output frequencies caused by the capacitance of the common node of the switch transistors. For this purpose, a replica switch is provided, with the voltage change on the common node of the replica switch being used to provide a corresponding charge to the common node of…
Controlling the extinction ratio of optical transmitters
Granted: October 19, 2004
Patent Number:
6807209
A system and method for stabilizing an extinction ratio for an optical transmitter that uses a laser diode that is modulated by a laser driver, the scheme having a modulating current and a bias current, wherein a portion of the bias current is fed forward into the modulating current to stabilize the extinction ratio and thereby improve a laser's performance over time and with increases in temperature.
Low power flip flop
Granted: October 12, 2004
Patent Number:
6803799
A low power, high speed D type flip flop is disclosed. The D type flip flop uses four inverters and four transmission gates to store and output the data states. The flip flop comprises two memory elements wherein each memory element is made up of a transmission gate and two inverters. Each of the four inverters contained in the flip flop is referred to as a bypass current limiting inverter. Each of the four inverters contains biasing circuitry to limit current flow and thereby save…
Switched-capacitor frequency-to-current converter
Granted: September 28, 2004
Patent Number:
6798372
A frequency-to-current converter operative to convert a clock frequency to an output current is described; the frequency-to-current converter ensures that the output current increases linearly with the clock frequency. The frequency-to-current converter may be incorporated in analog-to-digital converters driven by clocks with variable frequencies. The frequency-to-current converter employs an integrator circuit, used to compare an input reference voltage and a current feedback into a…
Fully digital symbol synchronization technique
Granted: September 28, 2004
Patent Number:
6799193
One aspect of the invention provides a novel scheme to synchronize signal reception for a receiver device. In one embodiment, multi-symbol correlation of a first signal and a reference signal is performed. The reference signal corresponds to symbols denoting a synchronization or alignment marker. For every first signal sample, an indication of the degree of similarity between a plurality of the first signal symbols and reference signal symbols is generate as a second signal. This second…
Semiconductor transistor having a polysilicon emitter and methods of making the same
Granted: August 10, 2004
Patent Number:
6773973
A polysilicon-emitter-type transistor has a substrate with a collector region, a base region on the collector region, and an oxide layer on the base region with an emitter window therein exposing part of the base region. The polysilicon emitter is formed by forming a first polysilicon layer of approximately 30 to 100 Angstroms at least within the emitter window and at least on the exposed base region. Then, an interfacial oxide layer being approximately 5 to 50 Angstroms thick is formed…
Method of forming self-aligned NPN transistor with raised extrinsic base
Granted: July 27, 2004
Patent Number:
6767798
A self-aligned bipolar transistor and a method of formation thereof are provided. The bipolar transistor has a raised extrinsic base such that the link base resistance is reduced by providing an extrinsic base which is thicker than the intrinsic base. The increase in thickness of the extrinsic base provides a less resistive layer of the heavily doped base region. The method of forming the bipolar transistor includes depositing a first epitaxial layer on a substrate to form a base region…
Low noise bandgap references
Granted: July 20, 2004
Patent Number:
6765431
Low noise bandgap references of the type providing a temperature independent output by balancing the proportional to absolute temperature dependence of the difference in base-emitter voltages of two transistors operating at different current densities with the negative temperature coefficient of the base-emitter voltage of a transistor. The bandgap references disclosed reduce the noise characteristic of such references by balancing the difference in base-emitter voltages of a first…
Alignment methods and apparatus for I/Q phase and amplitude error correction and image rejection improvement
Granted: July 6, 2004
Patent Number:
6760577
Alignment methods and apparatus for I/Q phase and amplitude error correction and image rejection improvement that may be used at the time of circuit fabrication or on chip for use during operation. The alignment method may be used to improve the I/Q phase and amplitude accuracy of a direct conversion transceiver or to improve image rejection in an up or downconversion mixer. For alignment purposes, a pilot tone of a selected frequency is used to provide a calibration reference, with…
Chopper chopper-stabilized operational amplifiers and methods
Granted: May 11, 2004
Patent Number:
6734723
An amplifier topology that combines the use of chopping and chopper stabilization, and may include auto-zeroing to achieve this very low offset. The use of choppers guarantees a very low offset, and moreover, eliminates the so-called 1/f noise. Chopper stabilization is used to avoid the so-called chopper noise associated with chopper amplifiers. The auto-zeroing technique may be used to improve the performance of the chopper-stabilization circuitry. Various exemplary embodiments are…
Current source array for high speed, high resolution current steering DACs
Granted: April 13, 2004
Patent Number:
6720898
Current source arrays having a plurality of current sources arranged in an array of columns and rows are disclosed. The outputs of the current sources in even rows of the first column of an array are connected to the output of a current source in each of the other columns located along a first diagonal through the array from the respective current source in the first column. Also the outputs of the current sources in odd rows of the first column of the array are each connected to the…
High efficiency, low noise frequency tripler and method
Granted: March 16, 2004
Patent Number:
6707344
High efficiency, low noise frequency tripler and method that generates an enhanced third harmonic of a frequency and suppresses the fundamental frequency component in the tripler output. The method comprises multiplying a constant plus a twice frequency component by a square wave at the fundamental frequency, such as by a modulator. The amplitude of the twice frequency component relative to the constant and the phase of the twice frequency component relative to the phase of the square…
Broadband RF mixer with improved intermodulation suppression
Granted: March 9, 2004
Patent Number:
6704559
An RF mixer circuit having reduced intermodulation products includes a cascode transconductance amplifier including a first transistor having a control electrode connected to receive an input signal and serially connected with a second transistor having a control electrode connected to receive a bias potential. A balanced mixer is coupled to the second transistor by a first inductive element for receiving an amplified input signal current, and receiving a local oscillator signal and…
Level-shift circuits and related methods
Granted: February 17, 2004
Patent Number:
6693489
A level shift circuit and method for level shifting the common-mode voltage of a power-supply-referenced circuit to the common-mode voltage of a ground-referenced circuit. The level shift circuit and method entails performing a common-mode level shifting of input complementary signals derived from the power-supply-referenced circuit to produce output complementary signals for the ground-referenced circuit. Because the level shifting is performed in a common manner (i.e. the level shift…
Method of forming self-aligned bipolar transistor
Granted: February 3, 2004
Patent Number:
6686250
A self-aligned bipolar transistor and a method of formation thereof are provided. The bipolar transistor has an emitter region characterized by a y-shaped structure formed from bilayer polysilicon. The bilayer polysilicon includes a first polysilicon emitter structure and a second polysilicon emitter structure. The method of forming the bipolar transistor includes forming an emitter stack on a substrate. The emitter stack comprises the first polysilicon emitter structure and a plug…
Thermal shutdown control for multi-channel integrated circuit boards
Granted: December 23, 2003
Patent Number:
6667868
A multi-channel power shut-down circuit that includes a plurality of channel disabler circuits formed on a common substrate where each of the channel disabler circuits includes a first combinational logic and a second combinational logic having an input coupled to an output of the first combinational logic and having a channel disable output, and a channel overcurrent detector coupled to an input of the first combinational logic. A thermal warning detector is also formed on the common…
Replica compensated heterogeneous DACs and methods
Granted: November 4, 2003
Patent Number:
6642867
Digital to analog converters having a hybrid two-stage structure. The first stage is a differential segmented current DAC controlled by the MSBs (most significant bits) of input data. The second stage is a resistor string DAC controlled by the LSBs (least significant bits) of the input data to interpolate between the differential outputs of the first stage. The resistor string is directly connected to the current DAC without the need of buffer amplifiers. Instead, a replica circuit is…
