Jammer detection based adaptive PLL bandwidth adjustment in FM receiver

US8437721B2 · kind B2 · utility

Assignee

• QUALCOMM Incorporated · US

Inventors

• Yi Zeng · San Jose, US
• Tzu-wang Pan · Irvine, US
• I-Hsiang Lin · Mountain View, US
• Jeremy Darren Dunworth · San Diego, US
• Pushp Trikha · San Diego, US
• Rahul Apte · San Francisco, US

Key dates

• Filing date: Apr 26, 2009
• Grant date: May 7, 2013
• Expiry date: Nov 24, 2031

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B1/1027
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A frequency synthesizer within an FM receiver employs a Phase-Locked Loop (PLL) to generate a Local Oscillator (LO) signal. The LO signal is supplied to a mixer. The FM receiver also includes jammer detection functionality. If no jammer is detected, then the loop bandwidth of the PLL is set to have a relatively high value, thereby favoring suppression of in-band residual FM. If a jammer is detected, then the loop bandwidth of the PLL is set to have a relatively low value, thereby favoring suppression of out-of-band SSB phase noise. By adaptively changing loop bandwidth depending on whether a jammer is detected, performance requirements on sub-circuits within the PLL can be relaxed while still satisfying in-band residual FM and out-of-band SSB phase noise requirements. By allowing the VCO of the PLL to generate more phase noise due to the adaptive changing of loop bandwidth, VCO power consumption can be reduced.