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Technical
FAQs
Here is a listing of some of the commonly asked questions about our products and technology. If you cannot find the answer to your question here, please contact tech support.
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Q: What is the Theta JC and Maximum Junction Temperature of the PE9xxx?
A: See table below for package thermal characteristics for all Hi-Reliability parts.
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Q: I am interested in learning more about your DuNE™/DTC products. Do you have any datasheets, and pricing information? When will these parts be available?
A: DuNE is a technology announcement, we have not yet announced any products for sale. Please stay tuned for product annoucements and sample availability.
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Q: I can't find the PExxxx listed on any of the product pages. Is that part still active and in production?
A: For a listing of our discontinued parts, please see our Discontinued Products Page.
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Q: Do you have a recommended PCB land pattern for the PExxxx?
A: We recommend that customers follow JEDEC recommended PCB land patterns. However, Peregrine EVK design files may be requested from Applications Engineering.
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Q: What is the MTBF of the PExxxx?
A: See our Quality page and download the Quarterly Reliability Report that contains MTBF calculations for all released parts.
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Q: Can I pass DC through your products? When are blocking capacitors used, and when can they be bypassed?
A: DC cannot be passed through our switches and DSAs. Blocking caps must be used when a non-zero DC voltage is placed on the RF pins. However, on our Prescalers, if the input is driven by rail-to-rail CMOS
and the output is drivng a large capactive load, blocking caps are generally not required.
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Q: What is the NVG/Charge Pump?
A: NVG is the Negative Voltage Generator. It is used in the biasing of our switches and DSAs. The NVG oscillator frequency is approximately 3MHz
and the amplitude is below -110dBm. Many parts contain a VSS bypass option where the user can provide an external VSS, disabling the on-board NVG.
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Q: What is the difference between Maximum Operating Voltage and Absolute Maximum Voltage?
A: The Maximum Operating Voltage is what we guarantee performance to, and is the limit for reliable operation over the product lifetime. If the instantaneous voltage exceeds the
Absolute Maximum Voltage, damage may occur. For reliable operation, please use the Maximum Operating Voltage as the upper limit.
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Q: What is the difference between Maximum Operating Power and Absolute Maximum Power, for the RF input?
A: There is only one Maximum Input Power, the power into 50ohms. Exceeding this power will compromise the long-term reliability of the part, and the part may not operate.
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Q: What about P1dB then?
A: The P1dB is just a figure of merit - the input power should not be raised to this level.
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Q: What happens if the Prescaler RF input level drops below the minimum indicated on the datasheet?
A: The Prescaler may oscillate. In order to suppress any oscillations, the device should be disabled when there is no signal or a weak signal. Some potential solutions are
disabling VDD when the Prescaler is un-used, and/or increasing the de-coupling on VDD and placing a shunt FET at the RF input that turns on only when there is no input or a weak input.
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Q: What is the load impedance that the Prescalers can drive? Can I cascade the Prescalers?
A: The maximum load capacitance they can drive is 10pF-15pF. When driving higher impedance loads, the output can be treated as a CMOS output driving a capacitive load.
As the load impedance gets higher, the transition edges become faster. The output voltage swing will approach rail-to-rail and in some low frequency cases, a squarewave output.
The Prescalers can be cascaded to increase the divide ratio. If the output of one Prescaler has a large output swing, the subsequent cascaded
Prescaler can be driven directly without the need of an AC coupling capacitor. Also, you want to make sure that the minimum RF power is met or else the Prescalers will oscillate.
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Q: What is the Prescaler input impedance?
A: In general, the input impedance is a large capacitance in parallel with a large resistance (on the order of 25k).
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Q: Can I use the Prescalers with AM modulation?
A: We don’t recommend that, as it will compromise the signal quality.
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Q: I don't see any Phase Noise information for your Prescalers. Can you provide that?
A: Our Prescalers demonstrate 20log (/N) Phase Noise improvement. Please contact Applications Engineering for documentation recommending how to make Prescaler PN measurements.
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Q: For the Prescalers, what happens when VDD drops below the minimum supply voltage? Will the part still divide or will it latchup high or low?
A: Peregrine's devices are immune to latchup. If you drop the VDD voltage below the minimum, the part will still divide, but with an elevated noise floor and reduced output power.
Eventually, of course, if you collapse VDD the part will no longer divide at all.
We can only guarantee datasheet performance within the recommended operating range for VDD.
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Q: In the Reflective Switches, what happens to the de-selected RF ports? Are they open-circuited?
A: In general, the de-selected RF ports are shunted to ground through the ON Resistance of the Shunt FETs, rendering the port short-circuited.
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Q: But what happens if I open-circuit the RF port that RFC is connected to?
A: The datasheet usually contains a Max Input Power spec into a 50ohm load. For a severe mismatch, i.e., open circuit, you can de-rate this number by 6dB.
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Q: Does the PE9601 accept a sine or square wave input?
A: If the Prescaler is bypassed, a Sine wave input is limited to 20MHz. Below 20MHz, a square wave is fine as long as the amplitude is large.
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Q: What are the differences between the PE3236 and PE3336?
A: The PE3236 and PE3336 are functionally the same. The Prescaler is the same and the Phase Detector has been optimized on the PE3336 for higher frequency operation.
There are minor differences between the parts, but one main difference is that the PE3236 does not have the internal pull down resistors.
Also, the PE3236 has lower minimum frequency limit of 200 MHz compared to 500 MHz for the PE3336. In addition, the PE3336 is offered in a Leaded 44L PLCC package or a Lead-Free 48L QFN package
For new designs, the PE3336 is recommended over the PE3236.
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Q: Can I drive the PE3341 with an LVDS input?
A: Yes, the PE3341 FIN and /FIN can be driven differentially with either LVPECL or LVDS. Each pin needs to be AC coupled because there is a DC bias on each input.
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Q: For the PE43x0x, can you explain the Switching Rate, Switching Time, and Settling Time specifications listed on the datasheet?
A: Switching Rate is the frequency at which you can change the attenuation state. We use an onboard NVG (Negative Voltage Generator) to provide VSS that is used in biasing the switch FETs. The Switching Rate of 25 kHz (40us) is set by the NVG recharge time. On some DSAs, there is a VSS bypass option which allows the user to externally provide VSS, eliminating the Switching Rate limitation.
Switching Time applies to the actual switching event itself. The Switching Time is measured from the point the control signal reaches 50% of final value to the point the output signal reaches within 10% of its target value. For example, for the PE43702, that number is 650ns.
Settling Time is similar to Switching Time, but instead the metric is within 0.05 dB of final value after control signal is at 50% of final value. For the PE43702, the Settling Time is 4us. This performance is significantly faster and more repeatable than competing GaAs technologies due to innate surface passivation in CMOS processing.
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