Circuit and method of amplifying a signal for a receiver

• US 6,133,793 A
• Filed: 07/27/1998
• Issued: 10/17/2000
• Est. Priority Date: 07/27/1998
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lau, Sin Kai Henry, Seneff, Timothy Ernest
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US09/122,730
• Time in Patent Office: 813 Days
• Field of Search: 330/301, 330/302, 330/306, 330/310, 330/311, 327/356, 327/359
• US Class Current: 330/302
• CPC Class Codes: H03F 2200/168 Two amplifying stages are coupled by means of a filter circuit
• CPC Class Codes: H03F 2200/72 the amplifier stage being a common gate configuration MOSFET
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence

Abstract

A transceiver (10) has a transmitter (12) and an image reject receiver (16). The image reject receiver (16) provides frequency translation of two modulated signals received from an antenna (14). The image reject receiver (16) has two mixers (22 and 32) to accomplish the frequency translation. One mixer (22) receives a modulated signal for GSM operation and the other mixer (32) receives a modulated signal for DCS/PCS operation. A local oscillator (24) generates another signal having a gain controlled by an amplifier (26) for supplying differential signals to both of the mixers (22 and 32). The amplifier (26) uses transistors (46 and 58) with inductors (40, 52, and 68) to generate the differential signals.

Claims

1. A receiver, comprising:

a local oscillator for supplying a signal;

an amplifier coupled for receiving the signal and supplying first and second differential output signals, wherein the amplifier includes,

a first transistor having a control terminal coupled for receiving a first reference voltage and a first current carrying terminal coupled for receiving the signal;

a first inductor having a first terminal coupled to a second current carrying terminal of the first transistor for supplying the first differential output signal;

a second transistor having a control terminal coupled for receiving a second reference voltage, a first current carrying terminal coupled to a second terminal of the first inductor, and a second current carrying terminal coupled for supplying the second differential output signal

a capacitor having a first terminal coupled to the first current carrying terminal of the first transistor and a second terminal coupled to the control terminal of the second transistor; and

first and second mixers each having a first input for receiving a modulated signal and a second input coupled for receiving the first and second differential output signals generated by the amplifier.

2. The receiver of claim 1, further comprising a first filter having an input coupled for receiving the modulated signal and an output coupled to the first input of the first mixer.

3. The receiver of claim 1, further comprising a second filter having an input coupled for receiving the modulated signal and an output coupled to the first input of the second mixer.

4. An amplifier, comprising:

a first inductor having a first terminal coupled to a first power conductor for receiving a first operating voltage;

a first transistor having a control terminal coupled for receiving a first reference voltage and a first current carrying terminal coupled to a second terminal of the first inductor;

a second inductor having a first terminal coupled to a second current carrying terminal of the first transistor;

a second transistor having a control terminal coupled for receiving a second reference voltage, a first current carrying terminal coupled to a second terminal of the second inductor; and

a third inductor having a first terminal coupled to a second current carrying terminal of the second transistor and to a terminal for receiving an input signal, and a second terminal coupled to a second power conductor for receiving a second operating voltage.

5. The amplifier of claim 4, further comprising a first capacitor having a first terminal coupled to the second current carrying terminal of the second transistor and a second terminal coupled to the control terminal of the first transistor.

6. The amplifier of claim 4, further comprising a resistor having a first terminal coupled to the first current carrying terminal of the first transistor and a second terminal coupled to the first power supply conductor.

7. The amplifier of claim 4, further comprising a second capacitor having a first terminal coupled to the second current carrying terminal of the first transistor and a second terminal coupled to the first current carrying terminal of the second transistor.

8. The amplifier of claim 5, further comprising a third capacitor that is connected in parallel with the resistor.