ADL5511 input S parameters

Question I want to integrate ADL5511 RF Detector in my application. Do you have any information regarding the input S parameters for the ADL5511? Answer I’ve attached the original s11 (converted from s1p to csv as well as an Excel file showing calculations for R and C. To get to return loss in dB, the power in dB would be 20*log(magnitude of complex quantity), since the complex quantity is measured as a voltage magnitude/phase by the analyzer.

ADL5511 be used for envelope detection in HPA and LPA applications?

Question Can the ADL5511 be used for envelope detection in HPA and LPA applications? Answer Yes, the ADL5511 has an envelope bandwidth of 130 MHz and a power detection range of 40 dB. This makes it feasible for this device to accurately detect the envelope of a modulated carrier with deep envelope modulation. In a so-called "drain modulation" application, the signal from the envelope output of this detector would be used to drive a fast switching power supply which would in turn drive the collector or drain of a power transistor.

difference between ADL5502 and ADL5511?

Question What’s the difference between ADL5502 and ADL5511? Answer For the most part ADL5511 is a higher performing part than ADL5502. It has higher detection range and envelope bandwidth. One nice feature of the ADL5502 that is not on ADL5511, is its peak hold function. So you can configure the envelope output of ADL5502 to hold the most recent peak that it has seen.

part with error performance less than 0.25 dB and low frequency of operation.

Question A customer is looking for help regarding the selection of RF detectors. They need a part with error performance less than 0.25 dB and low frequency of operation. Answer The ADL5511 is an excellent choice and can be configured to operate down to arbitrarily low frequencies.

ADL5511 resistor matching and formula 4 query (SR#: 1236843)

Question wrt to the ADL5511 datasheet, rev.0. page 19. The formula 4 is incorrect? There is a 2 in the numerator. Answer This is being acknowlegde and the 2 in the numerator is incorrect. Should be a 1 instead. Correction will be factored in for the next datasheet revision.

In the ADL5511 datasheet, pins 6, 7, 8, 12 and 13 are designated as No Connect. Are these pins really No-Connect or can I ground them?

Question In the ADL5511 datasheet, pins 6, 7, 8, 12 and 13 are designated as No Connect. Are these pins really No-Connect or can I ground them? Answer Pins 6, 8, 12 and 13 are not internally wire-bonded to the die so it's OK to ground these pins if you wish. However, Pin 7 is wire-bonded to the die so this pin should not be grounded.

How do you optimize the ADL5511 layout for best return losses?

Question How do you optimize the ADL5511 layout for best return losses? Answer Follow the layout of the evaluation board, i.e. locate the external shunt resistor as close as possible to the AC-coupling capacitor and locate that cap as close as possible to the device. The 75 Ohm shunt resistor combines with the internal input impedance to provide 50 Ohm match across a wide bandwidth. If your application is narrow band, you could experiment with the size of this resistor to see if you can improve the return loss at your operating frequency. You could also experiment with an active match using inductors and capacitors.

How critical is capacitive loading on the Venv output?

Question How critical is capacitive loading on the Venv output? Answer If you want to take advantage of the full 130 MHz envelope bandwidth of ADL5511, you need to make sure not to heavily load Venv with high capacitances. If you are doing measurements in the lab, use a FET probe. This is not a stability issue. It’s simply the case that if you load Venv with capacitance, the response time that you see will slow down.

Can you use the ADL5511 with different input carrier frequency signals?

Question Can you use the ADL5511 with different input carrier frequency signals? Answer Using the ADL5511 with different input frequencies is not a problem. You basically need to configure the device to accept the lowest expected frequency and then it will work fine with all other (higher) frequencies. Please refer to the section of the datasheet entitled "Operation below 1 GHz/Envelope Filtering". This will explain the changes that need to be made to FLT1 and possibly FTL3 and FLT4.

ADL5511 in an AGC loop application

Question A customer is using the ADL5511 in an AGC loop application, by applying a sine wave at different power levels using a signal generator and using the Vrms output pin to measure the output. They have a 75 Ohm resistor connected between pin 2 (RFIN) and ground. The circuit is not behaving as it should. Answer The RF input needs to be AC-coupled and the 75 Ohm resistor to ground should not be connected directly to pin 2 (RFIN). They may be pulling down the bias level on the RF input. The input frequency will determine whether they need caps on FLT2 and FLT.

building a FSK demodulator

Question A customer is building a FSK demodulator with the mark & space frequencies being 18KHz & 20KHz respectively. They require an envelope detector for the process, and have chosen the ADL5511. But, according to the guidelines provided in its datasheet, high valued capacitors up to 0.68uF are required to be connected at the FLT1, FLT2 & FLT3 pins. They are using separate envelope detectors for mark & space frequencies, so differentiation between the two FSK frequencies is the matter of concern. Answer You can operate the device with arbitrarily large capacitors. The best advice is to purchase an evaluation board to test out whether you can effectively demodulate the FSK signal in your application.

ADL5511 No Connect (NC) Pins

Question: In the ADL5511 datasheet, pins 6, 7, 8, 12 and 13 are designated as No Connect. Are these pins really no-connect or can I ground them? Answer: Pins 6, 8, 12 and 13 are not internally wire-bonded to the die so it's ok to ground these pins if you wish. However, Pin 7 is wire-bonded to the die so this pin should not be grounded.

S-Parameters for ADL5511 RF Input

Question: Do you have an S-Parameter file for the RF input of ADL5511? Answer: S-Parameter file is attached. Note that this is with the default external 75 Ohm shunt resistor removed. Attachments: ADL5511S11.csv.zip

ADL5511 VRMS and VENV Response Time to VPOS Turn-On

Q. The datasheet for ADL5511 shows the output response time when the ENBL pin is pulsed. What do the VRMS and VENV response times look like when VPOS is pulsed on and off. A. The attached plots show the response of VRMS when VPOS is pulsed for different values of CRMS (i.e. open, 10nF, 100nF and 4.7 nF). As you can see, the VRMS rise time following the turn on of VPOS has a strong dependency on the value of CRMS. With CRMS set to 0.1uF, there is are slight rise and fall time glitches. These glitches never exceed the settled value of VRMS. VRMS response to turn on of VPOS, CRMS = 0.1uF, Cdecl = 0.1uF, Pin = +1dBm Increasing the value of CRMS lengthens the turn on time. VRMS response to turn on of VPOS, CRMS = 4.7 uF, Cdecl = 0.1uF, Pin = +1dBm Decreasing the value of CRMS shortens the rise time with the rise and fall time glitches maintaining their character. VRMS response to turn on of VPOS, CRMS = 10 nF, Cdecl = 0.1uF, Pin = +1dBm Removing CRMS changes the shape of the VRMS response when VPOS is pulsed. This results in a sharp rising-side glitch. This is not a recommended mode of operation since without an rms averaging capacitor (CRMS) present, there is no correct rms computation taking place. VRMS response to turn on of VPOS, CRMS = open, Cdecl = 0.1uF, Pin = +1dBm With the RF input turned off, the following response was observed where VRMS exhibits small positive and negative glitches (approx. +200mV and -150mV) as VPOS is turned on an off. VRMS response to turn on of VPOS, CRMS = 0.1uF, Cdecl = 0.1uF, Pin = off The next plot shows the response of VENV when VPOS is pulsed. Note that the value of CRMS has no effect on the rise time of VENV VENV response to turn on of VPOS, CRMS = Not Applicable, Cdecl = 0.1uF, Pin = +1dBm With RFIN turned off, VENV jumps to its 1.1 V pedestal level when VPOS is pulsed on. This is shown in the last plot. VENV response to turn on of VPOS, CRMS = Not Applicable, Cdecl = 0.1uF, Pin = off For all of these measurements (except where noted) a continuous input power level of +1dBm was applied. The rise time of VPOS is affected by the presence of the power supply decoupling capacitors (0.1uF and 100pF).

ADL5511 Response to a Multi-Carrier Signal

Question: The datasheet shows the part working with a single 20MHz LTE carrier but can our part also function for 2 or even 3 carriers? Has anyone at ADI tested this? Answer: We have not tested the envelope response with multiple carriers. But we have measured the envelope bandwidth to be 130 MHz. We did this by sweeping the modulating frequency of an AM carrier at a fixed carrier frequency; we kept increasing the modulating frequency until the peak-to-peak of the output sine wave (i.e. the demodulated AM) was down by 3 dB. The ability of the ADL5511 to follow the envelope of a multi-carrier signal will be limited by the net bandwidth of the carriers. If it's two adjacent 20 MHz LTE carriers, it will work fine because the net bandwidth of 40 MHz is significantly ess than 130 MHz. If it's two carriers that are non-adjacent and separated by more than around 60 MHz (see Figure 39 in the datasheet which shows the response starting to fall at around 60 MHz), then the tracking is not going to be as good because the net bandwidth is equal to Fmax-Fmin. .