# US 5,703,912 A · Clock-recovery device having cascaded resonance amplifiers

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- Number: US 5,703,912 A
- Document ID: US5703912A
- Status: Granted
- Kind: A
- Application number: 08/646,236
- Filed: 1996-05-13
- Granted: 1997-12-30
- Earliest claimed: 1993-11-13
- Assignees: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
- Inventors: Zhigong Wang; Manfred Berroth
- Web page: https://patentgrep.com/patent/US5703912A

## CPC

- H03F 3/1935: {with junction-FET devices}
- H03D 7/1408: {with diodes}
- H03D 7/1441: {using field-effect transistors (H03D7/145 takes precedence)}
- H03D 7/1458: {Double balanced arrangements, i.e. where both input signals are differential}
- H03D 7/1491: {Arrangements to linearise a transconductance stage of a mixer arrangement}
- H04L 7/027: extracting the synchronising or clock signal from the received signal spectrum, e.g. by using a resonant or bandpass circuit
- H03D 7/125: {with field effect transistors}
- H03F: AMPLIFIERS
- H03D: DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers H01S; circuits capable of acting both as modulator and demodulator H03C; details applicable to both modulators and frequency-changers H03C; demodulating pulses H03K9/00; transforming types of pulse modulation H03K11/00; coding, decoding or code conversion, in general H03M; repeater stations H04B7/14; demodulators adapted for AC systems of digital information transmission H04L27/00; synchronous demodulators adapted for colour television H04N9/66)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A circuit for clock recovery from an input signal, particularly an alternating input signal formed from a data signal, the invention calling for a filter/amplifier unit made up of several series-connected resonance ampliers to be formed in a regenerative frequency filter. Unlike series-connected resonance amplifiers without feedback, the filter/amplifier unit has an overall Q-factor in the feedback loop which increases essentially linearly with the number of resonance amplifiers and their Q-factor. This enables the required high overall Q-factor to be obtained for the clock-recovery circuit with a relatively low number of resonance amplifiers with a Q-factor which is low compared with the overall Q-factor. A slope detector, a frequency mixer and the resonance amplifiers have similar assemblies so that the circuit can be designed more simply as a solid-state integrated circuit.

## Claims

### Claim 1

An apparatus for clock recovery from an alternating-voltage-carrying input signal which is formed from a digital data signal, said apparatus comprising a frequency mixer, said frequency mixer having first and second inputs and first and second outputs, said first input supplied with a signal that is assigned the clock frequency of an alternating-voltage-carrying input signal, and a filter and amplifier means for amplifying a narrow-band frequency range of an output signal of said frequency mixer, said filter and amplifier means including a filter and amplifier element having a high overall integrity, a feedback line transmitting an output signal of said filter and amplifier means to said second input of said frequency mixer, said filter and amplifier means including at least two series-wired filter and amplifier elements which comprise resonance amplifiers having tank circuits with inductances of monolithically integrated design, said resonance amplifiers having a low integrity as compared to the overall integrity of said filter and amplifier means, whereby the filter and amplifier means has high overall integrity and is formed of the cascaded resonance amplifiers, and is suited for amplification of a narrow-band frequency range of the output signal of the frequency mixer.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein each said resonance amplifier includes one differential amplifier with two field-effect transistors whose drains are interconnected via an inductance configured as a coil and which are connected by a diode to a circuit line, whose gates are connected to inputs of the resonance amplifier and whose sources are connected to a negative supply voltage via a constant-current source.

### Claim 3 (depends on 2)

The apparatus according to claim 2, wherein the field-effect transistors are connected to a safety circuit having two output field-effect transistors and two diodes, with the drains of the field-effect transistors each connected to the gate of an output field-effect transistor, the drains of the output field-effect transistors receiving a timing voltage, and the output field-effect transistor sources connected to supply voltage via forward-wired diodes as well as constant-current sources.

### Claim 4 (depends on 3)

The apparatus according to claim 3, wherein the field-effect transistors are coupled to two compensating field-effect transistors, a first compensating field-effect transistor connected with its drain to the drain of a first said field-effect transistor and with its gate to a gate of the second said field-effect transistor, the second compensating field-effect transistor connected with its drain to the drain of the second said field-effect transistor and with its gate to the gate of the first said field-effect transistor.

### Claim 5 (depends on 4)

The apparatus according to claim 4, wherein a capacitor interconnects the drains of the first said field-effect transistor and the first said compensating field-effect transistor and the drains of the second said field-effect transistor and the second said compensating field effect transistor.

### Claim 6 (depends on 2)

The apparatus according to claim 2, wherein the configuration of the resonance amplifiers is such that the output signal of the last resonance amplifier in the direction of signal travel is delayed as compared to the signal present on the first input of the frequency mixer by at least one-fourth of the clock period of the alternating-voltage-carrying input signal.

### Claim 7 (depends on 3)

The apparatus according to claim 3, wherein the configuration of the resonance amplifiers is such that the output signal of the last resonance amplifier in the direction of signal travel is delayed as compared to the signal present on the first input of the frequency mixer by at least one-fourth of the clock period of the alternating-voltage-carrying input signal.

### Claim 8 (depends on 4)

The apparatus according to claim 4, wherein the configuration of the resonance amplifiers is such that the output signal of the last resonance amplifier in the direction of signal travel is delayed as compared to the signal present on the first input of the frequency mixer by at least one-fourth of the clock period of the alternating-voltage-carrying input signal.

### Claim 9 (depends on 5)

The apparatus according to claim 5, wherein the configuration of the resonance amplifiers is such that the output signal of the last resonance amplifier in the direction of signal travel is delayed as compared to the signal present on the first input of the frequency mixer by at least one-fourth of the clock period of the alternating-voltage-carrying input signal.

### Claim 10 (depends on 1)

The apparatus according to claim 1, wherein the configuration of the resonance amplifiers is such that the output signal of the last resonance amplifier in the direction of signal travel is delayed as compared to the signal present on the first input of the frequency mixer by at least one-fourth of the clock period of the alternating-voltage-carrying input signal.

### Claim 11 (depends on 10)

The apparatus according to claim 10, including two delay lines interconnecting said frequency mixer and last resonance amplifier for delaying the output signal of the last resonance amplifier.

### Claim 12 (depends on 1)

The apparatus according to claim 1, wherein each said resonance amplifier includes one differential amplifier with two field-effect transistors whose drains connect via an inductance configured as a coil and which are connected by a diode to a circuit line means: whose gates are connected to inputs of the resonance amplifier and whose sources are connected to a negative supply voltage via a constant-current source.

### Claim 13 (depends on 1)

The apparatus according to claim 1, wherein the configuration of the resonance amplifiers is such that the output signal of the last resonance amplifier in the direction of signal travel is delayed as compared to the signal present on the first input of the frequency mixer by at least one-fourth of the clock period of the alternating-voltage-carrying input signal.