Low Noise VCOs

Descriptions

Low phase noise, a center frequency of 80 MHz, actuation range of several 100 kHz, aaa dBm output

Prototype model

• Designed by Y. Enomoto (2018), aiming at quick implementation, inspired by LIGO low noise VCOs. JGW-D1808968

• One unit costed 370,000 JPY. A rough estimation of the cost can be found in the attached spread sheet.

Noise performance

• Worse than the specification for the non-divided phase noise (klog 7425) at 1 and 10 kHz. See the table below.

• Most of the RF components are not secured to the chassis in order to allow for the quick implementation. This may cause undesired acoustic coupling.

• 

  • Frequency [Hz]	Measured noise in [Hz/Hz1/2 ] that converted in [dBc/Hz]	Spec. values without dividers in [Hz/Hz1/2] and in [dBc/Hz]
    0.01	5 (51 dBc/Hz)	--
    0.1	0.4 (9 dBc/Hz)	--
    1	0.1 (-23 dBc/Hz)	--
    10	0.05 (-49 dBc/Hz)	--
    100	0.05 (-69 dBc/Hz)	--
    1,000	0.05 (-89 dBc/Hz)	0.02 (-98 dBc/Hz)
    10,000	0.03 (-113 dBc/Hz)	0.01 (-123 dBc/Hz)
    100,000	--	0.01 (-143 dBc/Hz)

    As for the phase noise conversion, we have used L(f) = S(f)/2 where L(f) is that in [dBc/Hz] and S(f) is phase noise in [rad²/Hz] according to the IEEE definition.

Tuning Range

• Linear range of 0.8 to 2.8 V achieved (klog 6544, klog 6638). This is smaller than the expected range of 0-5 V.

• Resulting frequency showed some kind of hops, limiting the linear range. No clear explanation exists at the moment.

• Tuning sensitivity of 0.42 MHz/V is achieved (klog 6544). This is consistent with the specification of ROS-102-919 whose sensitivity is 4.5 MHz/V typ.

• 

Endeavour model

• Sophisticated version of the prototype model.
• The below is a list of the things that need to be evaluated before building it.
  1. Determination of whether ROS-102-919 meets the data sheet values in phase noise.
  2. Identification of where the dominant noise sources are.
  3. Identification of where the frequency hop comes from.
  4. Estimate the impact of thermal fluctuation through the push in VCO.

Improvements over the previous version

• Several points will be improved as listed below.
  • Mechanically stable mounting by providing an aluminum plate as was done for the RF distribution amplifiers and similar ().
  • Any others?

Bill of Materials

• Description	Part number	Manufacture	Notes	Price/each	Quantities	Total Price	Procurement/Preparation Status
  Seed VCO	ROS-102-919 (with eval.board TB-10)	Minicicruits	center freq. 100 MHz	19,400 JPY	3		arrived (2019/Aug; KI)
  RF amp for VCO output	LNBA-0-13-BJ-100-15	Wenzel		$411	2		Order placed (2019/Aug/23rd; KI) and arrived (2019/Nov/8)
  RF amp for LO	LNBA-10-23-AE-100-15	Wenzel	+23 dBm output	$448	2		s/a
  RF amp for the output signal	LNBDA-2-26-AC-AE-100-15	Wenzel	+26 dBm output	$754	2		s/a
  Frequency divider	LNFD2-10-100-13-1-13-15	Wenzel	factor of 10	$486	2		s/a
  Low noise Mixer	LNMX-X-X-X	Wenzel	no attenuation	$396	2		s/a
  1U Chassis for RF	JGW-D1706470-v1	AEL			2		AEL has several (2019/Jul/18)
  Narrow band pass filter	MC80-10-4AA	Lark Engineering	80 MHz		2		-
  Aluminum plates for heat sink			needs to be designed		2		-
  Low noise power unit for RF					2		-
  Ceramic capacitors for noise reduction	RCE5C1H103J1K1H03B	Murata	10 nF		5
  SMA barrel connectors					many
  SMA right angle connectors					many