Integrated RF front end with stacked transistor switch

• US 8,559,907 B2
• Filed: 03/05/2012
• Issued: 10/15/2013
• Est. Priority Date: 06/23/2004
• Status: Expired due to Fees

• Current Assignee: pSemi Corporation (Murata Manufacturing Co Limited)
• Original Assignee: Peregrine Semiconductor Corporation (Murata Manufacturing Co Limited)
• Inventors: Burgener, Mark L., Cable, James S.
• Primary Examiner(s): TRAN, PABLO N
• Application Number:
  US13/412,463
• Publication Number:
  US 20120252384A1
• Time in Patent Office: 589 Days
• Field of Search: 455/333, 455/127.3, 455/341, 455/127.1, 455/127.2, 455/121, 455/126, 455128-129, 455/339, 330/311, 330/277, 330/287, 330/251, 330/136, 330/310, 330/295, 330/124.R, 330/10, 247/341, 247280-281, 247/472
• US Class Current: 455/333
• CPC Class Codes: H01L 27/0248 for electrical or thermal protection, e.g. electrostatic discharge [ESD] protection
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/223 with MOSFET's
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/61 the cascode amplifier has more than one common gate stage
• CPC Class Codes: H03F 3/189 High-frequency amplifiers, e.g. radio frequency amplifiers
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/21 with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/2171 with field-effect devices H03F3/2173 - H03F3/2178 take precedence
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602
• CPC Class Codes: H03G 11/00 Limiting amplitude; Limiting rate of change of amplitude ; Clipping in general
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04B 1/0053 with common antenna for more than one band
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/48 : in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter H04B1/46 takes precedence
• CPC Class Codes: H04L 27/04 : Modulator circuits; Transmitter circuits

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.

Claims

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.

2. The RF front-end circuit of claim 1, further comprising a rectangular wave conditioner having an input coupled to the amplified transmit signal, an output coupled to the RF PA input node, and being configured to adjust a waveshape and duty cycle of the amplified transmit signal to generate a rectangular wave having a duty cycle that is particularly suitable for the RF PA input node.

3. The RF front-end circuit of claim 2, wherein the rectangular wave conditioner includes a control section configured to adjust the duty cycle of the rectangular wave coupled to the RF PA input node under control of a duty cycle control signal coupled to the rectangular wave conditioner.

4. The RF front-end circuit claim 1, wherein the RF PA includes a switching circuit disposed between an output drive node and a circuit common, configured to avoid linear operation and substantially operate at only a minimum impedance or a maximum impedance, and a radio frequency choke (RFC) coupled between the output drive node and the regulator circuit.

5. The RF front-end circuit of claim 4, wherein the switching circuit of the RF PA comprises a plurality of series-connected FETs of common polarity that are configured to divide maximum voltage stresses applied to the switching circuit approximately equally between themselves.

6. The RF front-end circuit claim 5, wherein the plurality of series-connected FETs is a multiplicity of series-connected FETs configured to switch on and off substantially concurrently with each other.

7. The RF front-end circuit claim 4, wherein the RF PA comprises only a solitary one of such switching devices, the solitary switching device consisting of one or more FETs that all conduct substantially concurrently, and further comprises a shunt filter disposed between the output drive node and a circuit common, the shunt filter being configured to conduct signal components of the power amplified transmit signal at one or more harmonics of an operating frequency fO through a significantly resistive impedance, while substantially rejecting signal components at fO.

8. The RF front-end circuit claim 7, wherein the shunt filter has an impedance that is a function of frequency, having local minimum values approximately equal to the power amplifier output characteristic impedance at frequencies of 2*fO and 3*fO.

9. The RF front-end circuit of claim 1, wherein the antenna-matched transmit signal has an operating frequency fO of at least about 900 MHz, and the integrated RF front-end circuitry is configured to deliver at least about 1 W of power to the antenna connection node at fO.

10. The RF front-end circuit claim 1, further comprising a second RF PA according with clause (b) but accepting an input signal at a second operating frequency fl and having a regulator circuit controlled by a signal from the transmit signal sensing circuit;

a second matching, coupling and filtering circuit according with clause (c) but configured to produce a second antenna-matched transmit signal;

wherein the antenna switch is further configured to controllably couple the antenna connection node exclusively to the second antenna-matched transmit signal, or exclusively to a second receive signal amplification path.

11. A method of fabricating an RF front end circuit, comprising:

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.