Integrated RF front end with stacked transistor switch
First Claim
1. An RF front-end 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 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. Stacks of multiple FETs in series to operate as a switching device may be used for implementation of the RF front end, and the method and apparatus of such stacks are claimed as subcombinations. An iClass PA architecture is described that dissipatively terminates unwanted harmonics of the PA output signal.
527 Citations
11 Claims
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1. An RF front-end 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 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. A method of fabricating an RF front end circuit, comprising:
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a) providing only one solitary antenna connection node for coupling the RF front end to an antenna, 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; 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 fO; 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