K-band VCO / Q-band Multiplier

CHV2240

Ref. :DSCHV22409336 - 02 Dec 09

5/8

Specifications subject to change without notice

Route Départementale 128 , B.P.46 - 91401 ORSAY Cedex - FRANCE

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Proposed external high Q resonator

This chip has been especially designed to be coupled to a high Q dielectric resonator. The

resonance is given by a dielectric cylinder coupled to a 50

Ω line. The size of the resonator

gives the centre frequency and the space between the resonator and the line gives the

loaded quality factor. The following drawing shows an example of external configuration.

Dielectric

resonator

Alumina substrate : thickness=250µm

50 Ohm resistance

via hole

3xl

2xl

d

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

Additional information

Resonator reference example = MURATA /DRD036EC016. As the exact

frequency is given by the resonator size but also by the environment (cavity size,

substrate characteristics, parasitic couplings …), the final dimensions of the

resonator have to be defined according to the definitive module design. Other kind

of resonators can be used (from TEKELEC or TRANS-TECH). The temperature

coefficient has to be chosen according to the environment.

Resonator coupling: d=0.2 to 0.3mm, l=1.5mm (quarter wave). These values

have been used in the test fixture, of course they can be modified if the

environment is different. The distance between the resonator and the edge of the

substrate (close to MMIC) is proposed to be 3xl=4.5mm (3 quarter waves),

theoretically only one is necessary but in this case the distance between resonator

and MMIC is too low for automatic assembly.

50

Ω

Ω

Ω

Ω line width on alumina (heigth=0.25mm) = 0.238mm

50

Ω

Ω

Ω

Ω load on alumina: this load has to be as good as possible (low parasitic

inductance).

Cavity size (mm) : 18 x 17 x 7

Recommendation for Frequency stability

In order to ensure a good frequency stability (versus temperature, external resonator

aging,…), it is recommended to use an external frequency locked loop with a low frequency

loop filter (below modulation frequency), or a PLL for both frequency modulation and

stability.