TRF372017EVM

Thanks so much for your reply. I just want to make certain that TRF372017 fits our project which has a rise cosine 5 MHz IQ signal input and requires a output of .5 to 2.5 GHz quadrature modulate RF signal. Is TRF372010 function like what the requirement described? In addition, to use TRF372010, which oscillator or do you have any recommendation, should we use to provide the clock signal send to TRF372010evm?

Hi Mingran,

Thanks for your reply.

Is TRF372010 function like what the requirement described?

TRF372017 is a high performance direct up-conversion device, integrating a high linearity, low noise IQ modulator and an integer-fractional PLL/VCO. The VCO uses integrated frequency dividers to achieve a wide, continuous tuning range of 300MHz–4800MHz. So TRF372017 can be fit for your system.

In addition, to use TRF372010, which oscillator or do you have any recommendation, should we use to provide the clock signal send to TRF372010evm?

There are 2 options, you could use the onboard 40.0MHz osicillator to provide reference clock or provide the reference clock externally. If you provide the reference clock externally, it should be less than 100MHz.

By default, the EVM is configured to use a 40-MHz VCO included on the board. Jumpers are included to allow the user to connect an external signal to connector
EXT_REF (J8). Remove JP3 and JP4 to use an external reference signal.

Sorry to bother your guys again, I have some final questions before purchase. 

1. Can we use the TRF372017EVM without connecting to computer interface? We want to the kit controlled by microcontroller with individual power source. In another words, can it setup with the software on the computer, then keep working functional with disconnect to computer.  
2. can we control output power? The output power of the signal should be adjustable from -5dbm to 5 dbm as our the requirements. Can this be done via the TI board?  

Thanks so much.

Hi Mingran,

1. We  can use TRF372017 EVM without connecting to computer once it is programmed. We can configure the register first, then make sure TRF3720 is working properly, then we can disconnect it with computer.

2. We can only control LO output power by changing BUFOUT_BIAS in Register 5. It is used to change PLL output buffer reference bias current. However, we cannot control RF output power.

Thanks,

With regards,

Joyce Li

Thanks I am using TRG372017 EVM right now. I found there is no description about port J2. In the block diagram it is called EXT_VCO, can you talk details bout how does this port works.

In addition, is it possible that we can use a micro-controller instead a PC to adjust the value of VCO, and how to do that?

Hi Mingran,

Ext_VCO means  External local oscillator input. User can provide external VCO to expand the synthesizer working frequency range.put. It is High impedance. Normally AC coupled.  EN_EXTVCO powers the input buffer and selects the buffered external signal instead of an internal VCO. Dividers, the pfd, and the charge pump remain enabled and may be used to drive an external VCO. NEG_VCO must correspond to the gain of the external VCO.

Second question, you can use MCU to control the SPI, just write the right register value to TRF3720 throug SPI communcation. As for adjust the value of VCO, The device contains logic that will automatically select the appropriate VCO and capacitor bank. Set bit EN_CAL to initiate the calibration algorithm. During the calibration process, the device will select a VCO and a capacitor state so that VTune matches the reference voltage set by VCO_CAL_REF_n.

Best regards,

Joyce

Great, Thanks so much.

I also notice that there are 2 connectors for I and Q baseband input for TRF372017EVM. How should I connect those with my I and Q input? I use a Agilent 33500b waveform generator to provide the IQ signals.

Hi Mingran,

There are 2 connectors for both of I and Q. They are differential IQ input: IP(I positive), IN(I negative); QP(Q positive), QN(Q negative). You can use baseband generator to generate differential IQ signal, just to make sure you connect them correctly.

Best regards,

Joyce

Hi Joyce,

That is the problem, our generator is single ended. Do you have any recommendation for the connector of differential inputs. 

Thank you. 

Hi Mingran,

You can provide singled-end signal to EVM IP and QP, and connect the other end to 50ohms.

Since you provide singled-end signal instead of differential signal, the output power level will be dropped. But you still can test its function.

Best regards,

Joyce

Thanks, just to make sure certain things.

Is it OK to just use a BNC-SMA coaxial cable connect from the BNC of waveform generator to SMA of TI?

Another question, for the 50 ohm does a SMA 50 ohm dummy load work or we should use some special components?

BTW, since we have so many questions, can you suggestion someone we could call to talk directly? 

Hi Mingran,

1. It is OK to use BNC-to-SMA connector to connect waveform generator to TI EVM.

2. For 50ohm load, you can use SMA 50ohm termination.

You can post your question in this E2E forum, and it is good to other readers, since other readers may have the same question. Thanks!

Best regards,

Joyce

Hello Joyce,

Thank you for your response. We buy the 50ohm terminations and they works good! 

Further questions: How to control the 372017EVM by a micro controller? I find the DATA, CLK and LE on TP10, TP9, TP7. But I did not find EN_CAL. And I need more details about how to program the DATA signal to get a required VCO frequency value. 

Mingran

Also, an easy question: 

What is the harmonic spec of 3720117EVM? My test results of the RF output signal is shown in graph. We want harmonic to be less than -35dbc/Hz. Is that possible to be done by TI board? Thank you.

Mingran,

TI has created a GUI to control the 372017EVM from your PC with a USB cable.  If you would like to use your own controller, you can use the Serial Peripheral Interface lines DATA, CLK, and LE on TP10, TP9 and TP7 that you indicated.  EN_CAL is not a test pin on the EVM but is the 31^st bit in register 2.  The Serial Interface Programming Register Definitions can be found on page 30 of the TRF372017 data sheet.  

Adam   

Adam,

We tried to control the VCO on the 372017evm via SPI. Based on the datasheet, I think that the the 6th bit to the 29th bit in Reg3 control the output frequency of VCO. However, when I send Reg3 to DATA pin, it does not work. How should we fix it?

Thank you.

Mingran

Mingran,

Based on the datasheet, the 5th bit to the 29th bit, in register 3, controls the fractional Phase Locked Loop N divider value 0 to 0.99999 not the output frequency of the VCO.  The fractional Phase Locked Loop N divider is a part of the the feedback loop from the Voltage Controlled Oscillator to the Phase Frequency Detector. 

For control of the VCO:

The TRF372017 includes four VCOs. Each VCO is connected to a bank of capacitors that determine its valid operating frequency. For any given frequency setting, the appropriate VCO and capacitor array must be selected. The device contains logic that will automatically select the appropriate VCO and capacitor bank. Set bit EN_CAL to 1 to initiate the calibration algorithm (Resets automatically).  Since a calibration begins immediately when EN_CAL is set, all registers must contain valid value prior to initiating calibration.  During the calibration process, the device will select a VCO and a capacitor state so that VTune matches the reference voltage set by VCO_CAL_REF_n.

Further information can be found at the bottom of page 44 in the datasheet under "Selecting the VCO and VCO frequency control"

Adam

Adam,

Does it mean that, after setting EN_CAL and VCO_CAL_REF_n bit, I should be able to control the VCO frequency by changing the voltage input via pin 38 VTUNE on 372017? But what is the voltage input range for pin 38?

Mingran,

After setting EN_CAL, the device will use an algorithm to select a VCO and a capacitor state so that VTune matches the reference voltage set by VCO_CAL_REF_n. Externally controlling the VCO frequency by changing the voltage input via pin 38 VTUNE will not make use of the Phase Lock Loop portion of the device and slight variations in the voltage supplied to pin 38 will cause variations in the VCO output frequency.  In order to stabilize the VCO output, there is a feed back loop from the VCO output to the phase frequency detector that compares the feedback VCO frequency/phase to the reference frequency/phase.  The phase frequency detector will detect the discrepancy in the two frequency/phases and control VTUNE accordingly to keep the desired frequency at the output of the VCO.  Here is a link to "PLL Fundamentals" that will talk about how VCOs work and their function in PLLs.

http://www.ti.com/lit/ml/snap001/snap001.pdf

Adam

Adam,

Sorry I am not quite understand what should I do here. Can you show me the simple step by step instruction on how to program the board to get a specific frequency output. For our project, we need to be able to output different RF frequencies from this device.

Thank you.

Mingran

Mingran,

There is a simple step by step instruction on how to program the board on the TI website called "TRF372017EVM User's Guide" http://www.ti.com/lit/ug/slwu068a/slwu068a.pdf.  There is also more information on programing the TRF372017 for specific frequencies with example calculations beginning on page 41 of the TRF372017 data sheet http://www.ti.com/lit/ds/slws224c/slws224c.pdf.

Adam

Adam, 

After careful reading the data sheet, it appears we must have input a reference signal on the REFIN pin. If this assumption is correct, in that, we must have our own reference signal in order to make the RF output frequency changeable? If the answer is "yes", we have the following questions:

1) what is the minimum frequency we can inject?

2) what is the maximum input signal level in voltage?

3) is the matching input impedance to REFIN 50 ohms?

Our project is due next week, please answer ASAP. Thanks so much!

Mingran

Mingran,

Yes, you need to have a reference signal on the REFIN pin to provide the phase/frequency detector a reference signal to compare to the signal being feed back from the voltage controlled oscillator.

You can find the information on the reference signal parameters on page 5 of the data sheet under "Reference Oscillator Parameters."

Adam