Intermediate frequency amplifier circuit for use in receive and transmit modes
First Claim
Patent Images
1. A high frequency amplification system, comprising:
- an off-chip filter and a high frequency amplification;
circuit integrated on a single substrate, the amplification circuit operating in a receive mode and in a transmit mode, the amplification circuit comprising;
a first switch having a receive input, a transmit input, and a common output;
a first amplifier having a first input and a first output, the first input coupled to the common output of the first switch, the first output coupleable to the off-chip filter;
a second amplifier having a second input coupleable to the off-chip filter and a second output; and
a second switch having a common input, a transmit output, and a receive output, the common input being coupled to the second output.
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Abstract
An intermediate frequency amplifier for wireless communication applications has the same receive path and transmit path through an off-chip filter. The intermediate frequency amplifier circuit includes a first amplifier and a second amplifier. The second amplifier includes a gain control circuitry. The second amplifier provides gain control for both the receive mode and for the transmit mode of operation. The IF amplifier can be used in a variety of communication applications, including cordless telephones, cellular phones, PHS phones, wireless modems, radios, and other devices.
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Citations
20 Claims
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1. A high frequency amplification system, comprising:
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an off-chip filter and a high frequency amplification;
circuit integrated on a single substrate, the amplification circuit operating in a receive mode and in a transmit mode, the amplification circuit comprising;
a first switch having a receive input, a transmit input, and a common output;
a first amplifier having a first input and a first output, the first input coupled to the common output of the first switch, the first output coupleable to the off-chip filter;
a second amplifier having a second input coupleable to the off-chip filter and a second output; and
a second switch having a common input, a transmit output, and a receive output, the common input being coupled to the second output. - View Dependent Claims (2, 3, 4, 5, 6, 7)
a gain control circuit coupled to the second amplifier, the gain control circuit adjusting the gain of the second amplifier.
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5. The amplification system of claim 4 wherein the gain control circuit includes a resistive network.
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6. The amplification system of claim 1 wherein the receive input and the transmit input are differential inputs, the first output is a single output, the second input is a single input, and the second output is a differential output.
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7. The amplification system of claim 1 wherein the first and second switches are unidirectional.
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8. An intermediate frequency amplifier system, comprising:
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an off-chip filter; and
an intermediate frequency amplifier;
circuit integrated on a single semiconductor substrate and for use in a receive mode and in a transmit mode, the intermediate frequency amplifier circuit comprising;
a first intermediate frequency switch circuit having a receive input, a transmit input, and a first switch output;
a first amplifier circuit having a first amplifier input and a first amplifier output, the first amplifier input coupled to the first switch output;
a second amplifier having a second amplifier input and a second amplifier output, the second amplifier input being in communication with the first amplifier output through the off-chip filter; and
a second intermediate frequency switch circuit having a second switch input, a transmit output, and a receive output;
the second switch input being coupled to the second amplifier output, wherein the intermediate frequency amplifier circuit has a unidirectional signal path through the first and second amplifiers for both the receive mode and the transmit mode.- View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
a gain control circuit coupled to the second amplifier, the gain control circuit adjusting the gain of the second amplifier.
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11. The intermediate frequency amplifier circuit of claim 8 wherein the first amplifier is a totem pole amplifier.
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12. The intermediate frequency amplifier circuit of claim 8 wherein the second amplifier includes a common gate amplifier and a common source amplifier.
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13. The intermediate frequency amplifier circuit of claim 10 wherein the gain control circuit includes a resistive network and FET switches.
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14. The intermediate frequency amplifier circuit of claim 8 wherein the circuit is implemented on a GaAs substrate.
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15. The intermediate frequency amplifier circuit of claim 8 wherein the first and second amplifiers include MESFETs.
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16. An intermediate frequency amplifier system, comprising:
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an off-chip filter; and
an intermediate frequency amplifier circuit integrated on a single semiconductor substrate and having a receive mode and a transmit mode, the intermediate frequency amplifier comprising;
first intermediate frequency switch means for coupling a receive input to a first switch output in the receive mode and for coupling a transmit input to the first switch output in the transmit mode;
first amplifier means for amplifying a signal on the first switch output;
second amplifier means for amplifying the amplified signal from the first amplifier means the off-chip filter being coupled between the first amplifier means and the second amplifier means; and
a second intermediate frequency switch means for coupling a receive output to the second amplifier means in the receive mode and for coupling a transmit output to the second amplifier means in the transmit mode. - View Dependent Claims (17, 18, 19, 20)
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Specification