Variable gain amplifier for low voltage applications
First Claim
1. A method for controlling transconductance gain of a complementary differential amplifier having first and second differential pairs of transistors, comprising:
- applying a first input voltage to a first transistor gate of the first differential pair of transistors;
applying a second input voltage to a second transistor gate of the second differential pair of transistors; and
varying a current source for at least one of the first and second differential pairs of transistors to control transconductance gain of the complementary differential amplifier for varying input voltages.
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Accused Products
Abstract
An integrated communications system. Comprising a substrate having a receiver disposed on the substrate for converting a received signal to an IF signal. Coupled to a VGA for low voltage applications and coupled to the receiver for processing the IF signal. The VGA includes a bank pair having a first bank of differential pairs of transistors and a second bank of differential pairs of transistors. The bank pair is cross-coupled in parallel, the IF signal is applied to the bank pair decoupled from a control signal used to control transconductance output gain of the bank pair over a range of input voltages. A digital IF demodulator is disposed on the substrate and coupled to the VGA for low voltage applications, for converting the IF signal to a demodulated baseband signal. And a transmitter is disposed on the substrate operating in cooperation with the receiver to establish a two way communications path.
64 Citations
8 Claims
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1. A method for controlling transconductance gain of a complementary differential amplifier having first and second differential pairs of transistors, comprising:
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applying a first input voltage to a first transistor gate of the first differential pair of transistors; applying a second input voltage to a second transistor gate of the second differential pair of transistors; and varying a current source for at least one of the first and second differential pairs of transistors to control transconductance gain of the complementary differential amplifier for varying input voltages. - View Dependent Claims (2, 3)
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4. A method for controlling transconductance gain of a complementary differential amplifier over a range of input voltages, the complementary differential pair amplifier having first and second differential pairs of transistors, comprising:
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applying a first input voltage to a first transistor gate of the first differential pair of transistors; applying a second input voltage to a second transistor gate of the second differential pair of transistors; varying a current source for at least one pair of the differential pairs of transistors to control transconductance gain of the complementary differential amplifier for varying input voltages; and applying a differential reference voltage across a resistive ladder connected between respective second transistor gates of the first differential pair of transistors and respective first transistor gates of the second differential pair of transistors. - View Dependent Claims (5, 6, 7, 8)
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Specification