HP 70427A User Manual page 450

Table 13-6 The phase noise performance is as follows:
Offset
Frequency
1 Hz
10 Hz
100 Hz
1 kHz
>10 kHz
The phase noise performance is achieved by using very high-Q crystal
resonators with very small burst noise, a circuit topology that is inherently
low noise, an active device which maintains good residual noise
performance as an amplifier even while limiting, and by paying special
attention to oscillator bias supply voltages. The capacitance multiplier
regulators on both the oscillator's emitter and collector supplies greatly
reduce the power supply noise which would be converted to phase noise in
the oscillator. The 100 MHz output amplifier collector supply is also
regulated to prevent noise degradation.
The regulators also improve 40 kHz spurs generated by the module's 40 kHz
switching power supply. Vibrational spurs induced in the crystal resonator
structure are reduced by vibration shock mounting of the 600 MHz
Reference Assembly.
The 100 MHz output amplifier has four outputs. The main output is
connected to the 600 MHz multiplier. The output level is +20 dBm, ±2 dB.
The outputs to the rear panel are +8 dBm and –2 dBm respectively, both ±2
dB. The output to the 80 dB isolation amplifier is 0 dBm, ±2 dB. The 100
MHz oscillator and outputs amplifier are always active during normal
module operation. The main 100 MHz output to the 600 MHz
multiplier/clean-up PLL must be turned off to prevent 100 MHz spurs in the
600 MHz NO TUNE and 5 ppm/V tuning sensitivity modes. Both these
criteria are satisfied by adding a 100 MHz output relay. The output relay
switches the main 100 MHz on, or terminates the amplifier output and the
input to the 600 MHz multiplier in 50Ω. The 50Ω termination of the
amplifier path is necessary for proper operation of the couplers between the
amplifier output and the output relay.
100 MHz Reference Loop (A7A1)
Typical Noise Oscillator Performance
Performance Requirements
Specified
–70 dBc –28 dBc
–100 dBc –78 dBc
–130 dBc –128 dBc
–160 dBc –158 dBc
–175 dBc –170 dBc
HP 70427A/HP 70428A User's Guide 13-15
Block Diagram
Typical
–25 dBc
–75 dBc
–125 dBc
–155 dBc
–167 dBc