Frequency synthesizer having phase control loop with plural branches

• Main Author: WUENSCH; CHRISTIAN
• Format: Patent
• Language: English
• Published: 19.10.1993
• Edition: 5
• Subjects: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATIONOF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES; BASIC ELECTRONIC CIRCUITRY; ELECTRICITY

The invention relates to a circuit arrangement for frequency synthesis with a phase control circuit (1) which comprises a first phase discriminator (3) for receiving a reference signal and an output signal supplied by a first frequency divider (6) with a division ratio k, a low-pass filter (4) coupled to the output of the first phase discriminator (3), and an oscillator (5) coupled to the output of the low-pass filter (4) for generating an output signal which can be supplied to the first frequency divider (6). At least one further branch (2) with a further phase discriminator (8) and a further frequency divider (9) which is to be released and which has a division ratio k is present. The further phase discriminator (8) coupled to the input of the low-pass filter (4) is designed for receiving the reference signal delayed by a delay element (10) and the output signal of the further frequency divider (9) provided for receiving the output signal of the oscillator (5). Each delay element (10) has a different delay time corresponding to a fraction of a period T=1/(n*fref) of the reference signal, n being the number of branches (1,2) and fref being the frequency of the reference signal. A control unit (11) releases the frequency divider (9) approximately after the delay time of the delay element (10) assigned to the relevant frequency divider (9).