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High-Density Passives
Voltage Tunable Capacitors
 Taking advantage of the unique ability of BST to change its capacitance density with an applied voltage Gennum has developed voltage tunable capacitors. BST film properties are engineered to provide a high degree of tunability (over 4 to 1) yet still maintain good loss performance. The high dielectric constant of the BST film allows for unparalleled miniaturization which coupled with our advanced metallization scheme produces low ESR and ESL electrodes resulting in excellent high frequency performance.
Tunability
Low ESR's are achievable into the GHz range.
Voltage tunable capacitors can be incorporated into capacitor networks which may include other types of capacitors having different functions and performance characteristics.
General Tunable Capacitor Design Parameters
|
| Parameter |
50/50 BST |
70/30 BST |
|
| Minimum Size: |
4 µm x 4 µm |
4 µm x 4 µm |
| Minimum Value
| ~ 0.3 pF |
~ 0.5 pF |
| Capacitance Density |
15-35 fF/µm2 |
25-60 fF/µm2 |
| Tunability (0V-10V) |
>2:1 |
>4:1 |
| TCC (below 0ºC) |
0.20%/V |
0.02%/V |
| TCC (above 0ºC) |
0.21%/V |
0.11%/V |
|
Example Tunable Capacitor Characteristics
|
| Parameter |
10 pF |
20 pF |
| 50/50 BST |
70/30 BST |
50/50 BST |
70/30 BST |
|
Self-Resonant Frequency
|
>8 GHz
|
>8 GHz
|
>6 GHz
|
>6 GHz |
| Tunability (0-4V) |
1.8:1
|
3.2:1
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1.8:1
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0.37 |
ESR @ 1 GHz, 0V
|
0.31
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0.53
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0.27
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0.37 |
ESR @ 2 GHz, 0V
|
0.27
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0.37
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0.22
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0.27 |
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Gennum can assist in the design, simulation (circuit and EM), and development of a customized BST capacitor network built to meet your needs. Contact us for more information.
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