PDQ - High Speed Charge Amplifiers
|PDQ Series High-Speed Charge Amplifiers with Dynamic Current Control
|Voltage||-30 V to 150 V*||-30 V to 200 V*|
||2 A||1.5 A|
|Overload Time||100 ms||100 ms|
|RMS Current||1.6 A||1.1 A|
|Signal Bandwidth||Greater than 80 kHz (1uF Load)|
|Power Bandwidth||9.5 kHz||7.2 kHz|
|Charge Gain||2.2, 6.2, 22, 62, 220, or custom uC/V|
|Voltage Gain||20 - 66 V/V|
|Offset||From 0V to Full-Range with front panel
|Input||Differential input stage that eliminates ground loops and noise. Zin = 22kohm|
|Connectors||BNC input, BNC Monitor Outputs,
2-Way LEMO 0B HV Output
||Thermal, current and voltage overload protection|
|Noise||less than 3mV RMS|
|Environment||0 - 40C (32-104F)
|Enclosure||Rugged desktop enclosure.
19 inch rack compatible.
|Dimensions||212.6 x 304.8 x 132.6 mm (w x d x h)|
|Power Supply||115 or 230/240 Vac|
(*) This is the minimum peak voltage. The actual voltage range will be larger.
The PDQ amplifiers are the first commercially available charge drives for piezoelectric actuators. A charge drive is similar to a voltage amplifier except that piezoelectric hysteresis can be reduced to less than 1%.
In many applications, a charge drive can immediately replace a voltage amplifier improved dynamic linearity is required reduce or eliminate the need for feedback or feedforward control of hysteresis.
Key features include:
- Elimination of actuator hysteresis
- -30V to 200V Output voltage range
- 2A peak output current
- Exceptional full-power bandwidth up to 9.5 kHz
- Exceptional bandwidth with large capacitive loads
- Front panel offset voltage adjustment 0V to 200V
- Comprehensive overload protection
- External shutdown
- Front panel monitoring of voltage and current
- Desktop or rack mounting options
The power bandwidth is the maximum frequency sinewave that can be reproduced at full voltage. The PDX150b and PDX200b are designed to maximize the power bandwidth in general purpose and scanning applications. With a capacitive load, the maximum frequency sine wave is:
where Vpp is the peak-to-peak voltage and C is the load capacitance.
Some values are tabluated below for typical load piezoelectric stacks capacitances as well as in the Power Bandwidth curve:
|Piezo Load |
||*9.5 kHz||*7.2 kHz|
||9.2 kHz||*7.2 kHz|
||4.2 kHz||2.3 kHz|
||1.4 kHz||790 Hz|
||424 Hz||230 Hz|
||141 Hz||79 Hz|
||42 Hz||23 Hz|
(*) With very small loads, the power bandwidth is limited by the slew-rate, which is approximately 4.5 V/us. This can be doubled to 8 V/us if necessary.
The differential input circuit eliminates ground-loops and noise resulting from the interconnection of different instruments.
The PDQ charge drives are preconfigured during manufacture to drive a certain range of capacitance values. This means that the charge-gain, resistance ratios, and transition frequency are all optimally preconfigured and do not require user adjustment. The standard capacitance ranges and associated chargegain, voltage-gain and cut-off frequencies are tabulated below.
|30 - 100 nF
||0.3 - 0.1 Hz||66 - 22||2.2 uC/V|
|100 - 300 nF
||0.1 - 0.03 Hz||60 - 20||6.2 uC/V|
|0.3 - 1.0 uF
||0.1 - 0.03 Hz||66 - 20||22 uC/V|
|1.0 - 3.0 uF
||0.1 - 0.03 Hz||60 - 20||62 uC/V|
|3.0 - 10 uF
||0.1 - 0.03 Hz||66 - 22||220 uC/V|
|10 - 1000 uF
The small-signal frequency response for a range of capacitive loads is shown in the figure and table below.
Note that the load capacitance is the maximum permitted under each charge range which results in a voltage gain of 20. When the load capacitance is lower, the voltage gain is increased and the bandwidth may reduce.
|Load Capacitance||Signal Bandwidth|
The PDQ drives are housed in a desktop enclosure that can be bolted together in a side-by-side configuration. Mounting in a standard 19-inch rack is also possible with the addition of rack-mount handles.The PDX amplifiers are housed in a desktop enclosure that can be bolted together in a side-by-side configuration. Mounting in a standard 19-inch rack is also possible with the addition of rack-mount handles.
The PDQ amplifiers can be customized to meet a range of industrial or scientific requirements. Specific options include:
- 19-inch rack kit for two amplifiers
- 19 inch rack kit for a single amplifier