EP0088467A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
FM receiver including a frequency-locked loop
Assignee: Koninklijke Philips NV
•
Filing: 1983-02-25
•
Granted: —
•
Expires: 2003-02-25
Abstract
Abstract FM-receiver including a frequency-locked loop (2-14), which loop includes, successively connected, a voltage controlled oscillator (8), a mixer circuit (2) connected to an aerial input, an IF-portion comprising an IF-filter (9), an FM-detector (4), a loop filter arrangement (5) and a loop amplifier (6) for adjusting the transfer characteristic of the frequency locked loop (2-14), which loop amplifier (6) is connected to a control input of the voltage-controlled oscillator (8) for a feedback of the modulation signal of the received FM-signal, which loop filter arrangement (5) comprises a first low-pass filter (14), the FM-receiver being realizable in integrated circuit form and suitable for processing FM-stereo signals. So as to ensure that for the processing of FM-stereo signals the receiver is at least comparable to conventional FM-stereo receivers as regards selectivity, harmonic distortion and stability which conventional FM-stereo receivers are not realizable in integrated circuit form, the stereo sum and the stereo difference signal being selectively and separately fedback via two simple, comparatively weakly selective parallel-arranged filter circuits (14; 18).
Inventors
- 👤 Wolfdietrich Georg Kasperkovitz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 22:25
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/001; H03D3/003; H03D3/004; H04; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/1646
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
167 words
An FM-receiver comprising a frequency-locked loop which includes, successively connected, a voltage-controlled oscillator, a mixer circuit also being connected to an aerial input, an IF-portion comprising an IF-filter, an FM-detector, a loop filter arrangement and a loop amplifier for adjusting the transfer characteristic of the frequency-locked loop, which loop amplifier is connected to a control input of the voltage-controlled oscillator for feedback of the modulation signal of the received FM-signal, the loop filter arrangement comprising a first low-pass filter, characterized in that the first low-pass filter selects the audio-frequency stereo sum signal from a stereophonic FM-multiplex signal, which loop filter arrangement also comprises a bandpass filter circuit arranged in parallel with the first low-pass filter for a selection of the stereo difference signal which is amplitude-modulated on a suppressed stereo sub-carrier from a stereophonic FM-multiplex signal, the phase shift of the first low-pass filter and the phase shift of the bandpass filter circuit being, at least within the passband of the frequency-locked loop, not more than 90°.
Claim 2
Dependent Claim
167 words
An FM-receiver comprising a frequency-locked loop which includes, successively connected, a voltage-controlled oscillator, a mixer circuit also being connected to an aerial input, an IF-portion comprising an IF-filter, an FM-detector, a loop filter arrangement and a loop amplifier for adjusting the transfer characteristic of the frequency-locked loop, which loop amplifier is connected to a control input of the voltage-controlled oscillator for feedback of the modulation signal of the received FM-signal, the loop filter arrangement comprising a first low-pass filter, characterized in that the first low-pass filter selects the audio-frequency stereo sum signal from a stereophonic FM-multiplex signal, which loop filter arrangement also comprises a bandpass filter circuit arranged in parallel with the first low-pass filter for a selection of the stereo difference signal which is amplitude-modulated on a suppressed stereo sub-carrier from a stereophonic FM-multiplex signal, the phase shift of the first low-pass filter and the phase shift of the bandpass filter circuit being, at least within the passband of the frequency-locked loop, not more than 90°.
Claim 3
Dependent Claim
47 words
An FM-receiver as claimed in Claim 1, characterized in that the first low-pass filter is a first order filter having a bandwidth of the order of 5 KHz, and the bandpass filter circuit is of the second order having a bandwidth of the order of 10 KHz.
Claim 4
Dependent Claim
94 words
An FM-receiver as claimed in Claim 1 or 2, characterized in that the bandpass filter circuit comprises, successively connected, a first mixer stage for demodulating the stereo difference signal which stereo difference signal is amplitude-modulated on a stereo sub-carrier within a stereophonic FM-multiplex signal, a second low-pass filter for selecting the demodulated baseband stereo difference signal and a second mixer stage for remodulating the baseband-stereo difference signal these two mixer stages being connected to an output of a stereo sub-carrier regenerator and the second low-pass filter having or approaching a first order frequency characteristic.
Claim 5
Dependent Claim
70 words
An FM-receiver as claimed in Claim 3, characterized in that arranged between the output of the stereo sub-carrier regenerator and at least one of the two mixer stages there is a phase shifting circuit for producing a phase shift of the regenerated stereo sub-carrier, the absolute value of this phase shift being at least substantially equal to the phase shift of the received stereo sub-carrier in the IF-filter and the.FM-detector.
Claim 6
Dependent Claim
62 words
An FM-receiver as claimed in Claim 4, characterized in that the output of the stereo sub-carrier regenerator is connected to the first mixer stage and via the phase shifting circuit to the second mixer stage, the phase shift of the regenerated stereo sub-carrier being equal but opposite to the phase shift of the received stereo sub-carrier in the IF-filter and the FM-detector.
Claim 7
Dependent Claim
65 words
An FM-receiver as claimed in anyone of the Claims 3 to 5, characterized in that an output of the second low- pass filter is connected to a first input of a matrix circuit and an output of the loop amplifier is connected to a second input of the matrix circuit for adding or subtracting, respectively therein the signals at said inputs of the matrix circuit.
Claim 8
Dependent Claim
28 words
An FM-receiver as claimed in Claim 6, characterized in that a variable-gain amplifier is arranged between the second low-pass filter and the first input of the matrix circuit.
Claim 9
Dependent Claim
44 words
An FM-receiver as claimed in any of the preceding Claims, characterized in that the stereo sub-carrier regenerator comprises a phase-locked loop a control input of which is coupled to the connection betweenan output of the FM-detector and an input of the loop filter arrangement.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.