The constraints
- 5V (~500mA) power from phone
- 1W RF output required
- Very compact with less "moving" parts
- 14 MHz capable
The design
We use INNOTION YG401530VB MMIC in this design.
100n
Si5351 CLK 0 --||----+---------+
| MMIC |
| IN |
| |
| OUT +----||---- RF OUT ---- LPF ---- 50R dummy load
+----+----+ 100nF
|
10uH
|
|---100n---GND
|
+5V
Note: No explicit 'special' matching required it seems ;)
This seems to be an extremely broadband circuit which should cover all HF!
Results
10 dBm from Si5351 and 13.8 dB gain of the INNOTION MMIC gives ~9.8Vpp output theoretically.
I am getting 10.8Vpp after a strong 20m BPF filter and into a 50 ohms load, which is roughly ~290 mW of RF power.
The goal however is to get around 1W - I need another 6dB gain it seems.
My idea: Condition the output of Si5351 by adding a 6ns fast comparator in series. This comparator will produce 5V square wave drive with 65mA plus current drive! Some attenuation after the comparator will be required.
Another possibility:
Si5351 -- 22Ω -- 74LVC1G04 @ 5V -- attenuator (3-6 dB) -- +14 dBm -- MMIC input
Another idea:
For +14 dBm into 50Ω, we need about:
P = 25 mW
Vrms = 1.12 V
Vpp sine ≈ 3.16 V
Ipk ≈ 32 mA
33Ω
ACT04 gate 1 ---/\/\---+
33Ω |
ACT04 gate 2 ---/\/\---+---- 6 dB pad ---- MMIC input
The ACT04 can do 24mA per output pin.
Compact idea:
SN74LVC2G04 / 74LVC2G04, two gates paralleled. Compact, fast, easy. Use one package with two inverters, parallel outputs through separate resistors:
Si5351---- gate1 ---- 22Ω ----+
+---- 3–6 dB pad ---- RF input
Si5351---- gate2 ---- 22Ω ----+
https://www.random-science-tools.com/electronics/dBm-Watts-volts.htm is very useful for doing the math.
Cost
The INNOTION MMIC costs around 30 INR - beat that! ;)
Time to build
Less than 30 minutes