INTEGRATED RF FRONT END
First Claim
1. Integrated RF front-end circuitry on a monolithic integrated circuit, comprising:
- a) an RF signal amplifier configured to receive a transmit signal having frequency content and phasing that is substantially suitable for transmitting, and to amplify such signal to establish an amplified transmit signal;
b) an RF power amplifier (PA) circuit having an input node coupled to an input signal derived from the amplified transmit signal, the RF PA being configured to amplify such input signal to generate a power amplified transmit signal having a power amplifier output characteristic impedance, and including a regulator circuit configured to controllably constrain an amplitude of the power amplified transmit signal;
c) a matching, coupling and filtering network configured to condition the power amplified transmit signal by blocking DC components, changing the characteristic impedance of the signal, and rejecting unwanted frequencies, to establish an antenna-matched transmit signal;
d) an antenna switch configured to controllably couple the antenna-matched transmit signal to an antenna connection node, or to decouple the antenna connection node from the transmit signal and couple the antenna connection node instead to a receive signal amplification path;
e) a transmit signal sensing circuit configured to generate a transmit power signal that reflects at least an amplitude of the transmit signal that is coupled via the antenna switch; and
f) a control circuit configured to cause the regulator circuit to constrain the power amplified transmit signal in response to the transmit power signal so as to substantially prevent the amplitude of the transmit signal coupled by the antenna switch from exceeding a predetermined limit.
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Accused Products
Abstract
A monolithic integrated circuit (IC), and method of manufacturing same, that includes all RF front end or transceiver elements for a portable communication device, including a power amplifier (PA), a matching, coupling and filtering network, and an antenna switch to couple the conditioned PA signal to an antenna. An output signal sensor senses at least a voltage amplitude of the signal switched by the antenna switch, and signals a PA control circuit to limit PA output power in response to excessive values of sensed output. Preferred fabrication techniques include stacking multiple FETs to form switching devices. An iClass PA architecture is described that dissipatively terminates unwanted harmonics of the PA output signal. A preferred embodiment of the RF transceiver IC includes two distinct PA circuits, two distinct receive signal amplifier circuits, and a four-way antenna switch to selectably couple a single antenna connection to any one of the four circuits.
63 Citations
16 Claims
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1. Integrated RF front-end circuitry on a monolithic integrated circuit, comprising:
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a) an RF signal amplifier configured to receive a transmit signal having frequency content and phasing that is substantially suitable for transmitting, and to amplify such signal to establish an amplified transmit signal;
b) an RF power amplifier (PA) circuit having an input node coupled to an input signal derived from the amplified transmit signal, the RF PA being configured to amplify such input signal to generate a power amplified transmit signal having a power amplifier output characteristic impedance, and including a regulator circuit configured to controllably constrain an amplitude of the power amplified transmit signal;
c) a matching, coupling and filtering network configured to condition the power amplified transmit signal by blocking DC components, changing the characteristic impedance of the signal, and rejecting unwanted frequencies, to establish an antenna-matched transmit signal;
d) an antenna switch configured to controllably couple the antenna-matched transmit signal to an antenna connection node, or to decouple the antenna connection node from the transmit signal and couple the antenna connection node instead to a receive signal amplification path;
e) a transmit signal sensing circuit configured to generate a transmit power signal that reflects at least an amplitude of the transmit signal that is coupled via the antenna switch; and
f) a control circuit configured to cause the regulator circuit to constrain the power amplified transmit signal in response to the transmit power signal so as to substantially prevent the amplitude of the transmit signal coupled by the antenna switch from exceeding a predetermined limit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An RF power amplifier (PA) configured to produce an output signal at an output drive node, the RF PA comprising:
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a) an input node configured to receive an RF input signal at an operating frequency f0;
b) a switching circuit configured to couple the output drive node to a circuit common through an “
on”
impedance, or to substantially decouple the output drive node from the circuit common, under control of the RF input signal, substantially avoiding linear operation;
c) an RF choke (RFC) coupled between a power source VDD and the output drive node, and configured to deliver current having a waveform that is substantially sinusoidal at f0 under control of the switching circuit operation; and
d) a shunt filter disposed between the output drive node and the circuit common and configured to conduct current through a terminating impedance ZT having a resistive component roughly equal to a resistive component of a characteristic output impedance Z0 of the RF PA for a component of the output drive signal having a frequency that is an integer harmonic of f0. - View Dependent Claims (12, 13, 14, 15)
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16. A method of fabricating an RF front end circuit on a single monolithic integrated circuit chip, comprising:
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a) providing only one solitary antenna connection node for coupling the RF front end to an antenna separate from the chip, and coupling the antenna connection node to i) a transmit signal sensing circuit configured to develop a signal reflective of a transmit signal amplitude, and ii) a common connection of an antenna switch that is disposed on the chip;
b) coupling an input signal node to a transmit signal amplifier configured to amplify a received transmit signal;
c) laying out a power amplifier (PA) having a switching circuit configured to operate in switching mode, without substantial linear operation, to switch an output drive node to circuit common, or not, under control derived from the amplified received transmit signal, such that the output drive node has a characteristic impedance Zdrive at an operating frequency f0;
d) coupling the PA output drive node to a first connection of an RF choke (RFC), and coupling a second connection of the RFC to a power source via a regulator circuit;
e) coupling the PA output drive node to an input of the antenna switch via a coupling, matching and filtering network such that a transmit signal thus switchably coupled to the antenna connection node has a characteristic impedance substantially equal to an expected impedance of a connection to the antenna;
f) coupling, to the antenna connection, an output signal sensing circuit configured to generate a signal reflective of excessive voltage at the antenna connection; and
g) coupling the signal reflective of excessive voltage at the antenna connection to the regulator circuit whereby the output drive signal amplitude is controlled to preclude the existence of significantly excessive voltage at the antenna connection.
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Specification