US 5,471,665 AGranted

Differential DC offset compensation circuit

AssigneeMotorola, Inc.

InventorsGary L. Pace, James D. Hughes

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Abstract

A differential direct current (DC) offset compensation circuit for providing DC offset compensation to a circuit device (110). The DC offset compensation circuit (100) comprises a differential integrator (120) and a summing network (130). The circuit device (110) is one of several types of devices, such as a DC coupled amplifier. The differential input (112) of the circuit device (110) is suitable for coupling to a differential input source (140) and the differential output (114) of the circuit device is suitable for connection to a load (150). The differential integrator (120) features a transconductance amplifier (18) at least one other amplifier (13), and a capacitor element (16) having a capacitance of C1. The summing network (130) sums the differential integrator output with the differential input signals of the differential input source (140) and cancels DC offsets of the differential input source (140) and the circuit device (110).

Claims21

Dependent claims

In combination, a receiver circuit for receiving a signal detected by an antenna, and a control circuit for controlling ON and OFF time of the receiver circuit, the receiver circuit comprising:

a radio frequency (RF) amplifier coupled to the antenna for amplifying the signal detected by the antenna and generating an amplified signal;
a mixer coupled to the RF amplifier for mixing the amplified signal with an oscillator signal of a predetermined frequency and generating at an output a mixed signal;
an amplifier stage coupled to the mixer comprising:
a first amplifier coupled to the output of the mixer for amplifying the mixed signal and generating at an output a first differential amplified signal;
a second amplifier DC coupled to the output of the first amplifier and having a predetermined frequency pass characteristic for amplifying the differential amplified signal and for generating at an output a second differential amplified signal;
a differential integrator coupled to the output of the second amplifier for receiving as input the second differential amplified signal and generating at an output a differential integrator output;
and
a summing network coupled to the output of the differential integrator and to the output of the first amplifier, the summing network summing the differential integrator output with the first differential amplified signal for canceling any DC offsets of the first amplifier and the second amplifier;
wherein the control circuit generates a receiver power control signal comprising a receiver ON time interval for turning ON the RF amplifier, mixer and amplifier stage, and a receiver OFF time interval for turning OFF the RF amplifier, mixer and amplifier stage.

6 more elements

In combination, a receiver circuit for receiving a signal detected by an antenna, and a control circuit for controlling ON and OFF time of the receiver circuit, the receiver circuit comprising:

a radio frequency (RF) amplifier coupled to the antenna for amplifying the signal detected by the antenna and generating an amplified signal;
a mixer coupled to the RF amplifier for mixing the amplified signal with an oscillator signal of a predetermined frequency and generating at an output a mixed signal;
an amplifier stage coupled to the mixer comprising:
an amplifier coupled to the output of the mixer for amplifying the mixed signal and generating at an output a differential amplified signal;
a differential integrator coupled to the output of the amplifier for receiving as input the differential amplified signal and generating at an output a differential integrator output;
and
a summing network coupled to the output of the differential integrator and to the output of the amplifier, the summing network summing the differential integrator output with the differential amplified signal for canceling any DC offsets of the amplifier;
wherein the control circuit generates a receiver power control signal comprising a receiver ON time interval for turning ON the RF amplifier, mixer and amplifier stage, and a receiver OFF time interval for turning OFF the RF amplifier, mixer and amplifier stage.

5 more elements

Dependencies are inferred from the claim text.