| US RE40,620 E1 | ||
| Fully integrated All-CMOS AM transmitter with automatic antenna tuning | ||
| Joseph S. Elder, Windermere, Fla. (US); Mohammed D. Islam, Orlando, Fla. (US); and Joseph T. Yestrebsky, Apopka, Fla. (US) | ||
| Assigned to Micrel, Inc., San Jose, Calif. (US) | ||
| Filed on May 23, 2005, as Appl. No. 11/134,468. | ||
| Application 09/837775 is a continuation in part of application No. 09/074997, filed on May 08, 1998, granted, now 6,253,068. | ||
| Application 11/134468 is a reissue of application No. 09/837775, filed on Apr. 17, 2001, now 6,658,239, filed on Dec. 02, 2003. | ||
| Claims priority of provisional application 60/046128, filed on May 09, 1997. | ||
| Int. Cl. H04B 1/04 (2006.01); H04B 1/18 (2006.01) | ||
| U.S. Cl. 455—121 [455/126; 455/125; 455/197.2; 455/193.1; 455/129; 455/91] | 52 Claims |
| [ 18. A transmitter having an automatic antenna tuning circuit, the transmitter comprising:
a transmit amplifier for being driven at a carrier frequency, the transmit amplifier for being connected to an antenna;
a variable capacitance, the variable capacitance and antenna forming at least part of a tuned circuit having a resonant frequency,
wherein varying the variable capacitance tunes the resonance frequency of the tuned circuit; and
a tuning circuit connected to control the variable capacitance in response to a feedback control signal, the feedback control
signal indicating whether the resonance frequency of the tuned circuit is matched to the carrier frequency, the tuning circuit
for varying the variable capacitance based on the feedback control signal to cause the resonance frequency of the tuned circuit
to match the carrier frequency,
at least the amplifier, variable capacitance, and tuning circuit being formed on a single integrated circuit.]
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